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Notice it randomly, could be a long trip or short trip. The idle tends to get higher when I stop, Finally noticed it the other day, popped it in neutral and it will idle at about 1200. When I put it back in drive it thunked so hard.. Then the shift points were messed up like I had the tow/haul on. Doesn't idle like this all the time.. just random. First thought it may be vaccum, but I"m not sure. Any suggestions?
Mine's doing the same thing minus the funky shift points. It's only started since it's been cold.
haha usually when mine is cold, it doesn't shift out of second until it warms up.. Have to let it sit for 10 minutes.. or it'll wind out second. Since it has warmed up a bit, figured that mihgt help though this morning, nope.. still did it on the way to napa to get some fuses.
I notice that a manual is harder to shift when its cold, which is probably the same way with auto. The fluid being cold, and thicker because its cold. Idling my does that too, until it warms up.
maybe the idle regulator motor? i only say that because in december, i had to have mine replaced.
EGR Valve? I am stumped, It happened to me again tonight in less than a mile and a half drive from a store to my house.. got in the neighborhood, pulled up to a stop sign.. bam.. idling at 1000.. popped it in neutral.. 12 - 1300, then back down to like 5 - 6(only twice though) then stayed up at like 1200.. put it in drive and it felt like i hit something it shifted so hard into drive..
There is no "regulator motor". Not sure what others had replaced. Faulty EGR will generally cause rough running and low idle speed.
You might want to post up what kind of truck we're talking about, information is king.
Depends on if it's DBC and has an IAC, is a old DBW with an IAC as well (I think those were only on utilities), or if it's new style DBW with no IAC. Also depends on if it's 04+ with the fuel system changes then.
You see?
I'd have to guess it's a 02-back DBC with an IAC problem or more likely a vacuum leak. Has the SES light been on?
There are a million things that could cause such issues, more information makes it easierest to figure.
No SES light.. Yet anyway. 2000 RCLB 5.3, Sorry for not stating that up front.
DBC/DBW IAC.. what exactly does that mean?
DBC = Drive By Cable
DBW = Drive By Wire
IAC = Idle Air Control
man, that valve is expensive.. I checked the vaccuum line that runs from the fuel rail to the top of the intake manifold.. its good.. no cracks or anything, where else should I be looking?
may have carbon buildup on the IAC valve, a bad TPS or MAP sensor, or just a vacuum leak somewhere. Is your brake booster hissing while the engine is idling? Even a dirty EGR valve can cause high idle issues.
When you pulled the vacuum line off did you check for fuel out of the regulator (on the rail). Usually doesn't cause the condition you've noted but it's an easy check. I'd lean towards a vacuum leak from the intake gaskets. Spray some break cleaner or carb cleaner around the base of the intake at idle and see if there's a noticable change in the idle speed and/or smoothness. Clean the throttle plate and MAF sensor. Pull the IAC out of the throttle body and make sure the passage is clean.
There wasn't any in the line from the fuel regulator up when I pulled it off.. I'll go ahead and try and run down those list of things that you gave me.. poke around.. see if I can't find something wrong.. I'll let you know how things go. Thanks for the help guys.
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I have the same problem in my 98' tahoe I'm gonna go get some carburetor and choke cleaner and go to town.
EDIT: Oh whoops gasguzzler already mentioned this.. In much more detail. Do as he said that is the problem that needs to be solved.
Finally got around to fooling with it.. It's been so windy the past couple days that I didn't even want to go outside. Sprayed carb cleaner everywhere.. all portions of the intake, checked MAF.. looked good.. tb at IAC had no blockage. all connections are good, no wires are bad.
Poissbly in load shed mode? This is when the BCM and PCM decide the voltage is low and they work together to shed electrical loads and raise the idle. Maybe engine protection mode? If the PCM thinks the engine is overheating it might do stuff like that.
Just a couple shots in the dark but you'll need scanned and logged (or snap-shotted with a TechII) to really know at this point.
Actually about a week and a half ago, went to go start my truck, flipped the key.. got nothing, no lights anything, couple minutes later, it started but was running very rough. The positive cable was loose.. tightened it up.. Got to love side posts.. Do you think that may have anything to do with it? You said something about voltage drops..
Mine did that exact same thing this morning. Wouldn't start. Went inside, Went back out and tried again for sh!ts and giggles and it started. Sounded more like a chopper trying to take off though. Thump Thump Thump Thump Thump Thump. Almost like I had a really Lopey cam.
Check engine light has been on for a while. Last time I had it read left and right bank lean. Don't know if that has anything to do with it. Still haven't changed them.
Could be. Take the cables off and remove the red and black boots. Make sure you get the cable ends clean before reinstallation. Replace the bolts if they're corroded.Quote:
Originally Posted by 4444xxxx4444
It's been 4 days and hasn't slipped up yet.. took off the boots, wire brushed the little amount of corrosion that was on the positive side.. put it back together.. Cleaned everything once again.. checked for issues in the TB and MAF. Something I did seems to be working. Thanks GAS for the advice and knowlege.
High idle returned worse than ever.. i've cleaned everything again and ran through all the stuff from before.. maf, IAC, throttle body, battery terminals.. it's everytime I start my truck. I'm afraid to drive it. had the driveshaft out of it the past couple days puttin new u joints in.. went and started it this afternoon and it won't seem to quit. Any other input would be appreciated. Thank you all in advance.
As I said a few posts ago mine does the exact same thing. my check engine light was on, rough idle, sputtering and so on. I remover my hypertech tune and my check engine light turned off, Idle is almost normal when cold, but once it warms up it's fine. Only thing that's still happening is it bogs down and it feels like it's gettin too much fuel/not enough air at WOT from a stop. Do you have any type of tuning device installed?
Did you have a backfire? You really need someone to smoke check your intake. You've probably got a leak, a crack, broken or cracked brake booster connection, bad brake booster, bad IAC valve or the TB blade isn't closing all the way down.
It started out when it was like 30 degrees outside.. i would let it warm up and it would be fine for a little bit.. all at random times though.. since then.. temperature jumped up to around 60 where i'm at the past couple days.. and today it has done it everytime i started the truck.. No tuning device, and i'll see what I can find out around here about having all that stuff checked out with the intake. I've tried spraying carb cleaner everywhere i could possibly think of to see if the idle fluctuates at all and I can't find anywhere that it does. I've got a clean lookin intake now though.
Finally threw a CEL for the TPS.. could this be the problem.. or an indirect problem from something else?
Nope....probably it. Wash your engine lately? These TPS will die when water gets in. The last three I've done a popped open to find them wet inside. :lol:
have washed it.. can't remember how long ago.. i know that i've done it.. I've got two different part numbers sittin at my house.. its just a matter of figurin out which is right and puttin it on